1. Field of the Invention
The present invention relates to an apparatus for printing characters onto both surfaces of a sheet material, and more particularly to an apparatus for printing letters, numerical characters and symbols in response to electronic data transmitted from a host machine such as a data processor of a computer onto both surfaces of a sheet of paper or film.
2. Description of the Prior Art
Printers such as a line printer are widely used as an output terminal equipment of various electronic data processors that output letters and numerical characters in response to electronic data input. Printers of this type are often capable of printing only on one side of a sheet material, and the other side of the sheet is wasted.
There are known printers for cut sheets that are provided with a mechanism for printing characters onto both surfaces. In such a printer, one of the sheet surfaces is printed with characters by the printer head and then carried forward by the carrier means, whereupon the sheet is turned either by manual or automatic operation. The now turned sheet is returned to the inlet of the carrier means, where the printer head prints characters on the thus turned back surface of the sheet material. Conventional printers of this type require an extra step of turning the sheet over after printing on one side has been completed, taking twice as long as the time required to print on one side only. In case of an automatic operation, an extra means is needed to turn the sheet over.
Printers used to print characters onto a continuous sheet material wound up into a roll or folded alternately into pleats along the cutting perforations are also capable of printing on only one side of a sheet, and none is capable of printing on both sides.